Cytokinins in shoot and root tissue were studied in plants of Plantago major L. ssp. pleiosperma (Pilger) grown on a concentrated and on a dilute nutrient solution. Cytokinins of plants transferred from the concentrated to the dilute solution were compared with plants treated similarly but with 10−8M benzyladenine (BA) added to the dilute solution. Cytokinin concentrations were also measured in plants that had been grown throughout on one of the two nutrient solutions. A restricted supply of minerals was correlated with low cytokinin concentrations. Transfer from a concentrated nutrient solution to a dilute solution depressed the cytokinin concentration by 50% within two days of transfer. This decline did not appear if similar plants were supplied with 10−8M BA in the dilute solution. The glucosides were the only major cytokinins enhanced by mineral shortage. This effect of low mineral supply was retarded but not entirely prevented by exogenous BA. The increased synthesis of glucosides in the BA‐treated plants was accompanied by lowered concentrations of free bases and their ribosides and of nucleotides. The sum of cytokinins in BA‐treated plants was thus similar to that in plants grown at the high mineral level. The results are discussed in relation to a possible role of cytokinins in regulating growth responses to changes in mineral nutrition.
Growth rates of roots and shoots of hydroponically grown plants of a salt resistant variety of barley decreased rapidly after an exposure to 65 M m -3 sodium chloride. This growth rate reduction tended to be temporarily and it was accompanied by a lowered shoot to root ratio. At the same time growth reduction took place, the cytokinin concentrations in root and shoot tissue decreased rapidly too, as they were measured by an enzyme-linked immuno assay. The addition of 5-10 9 Mm-3 benzyladenine (BA) retarded the decreases of growth rates, shoot to root ratio and internal cytokinin concentrations.Growth rates of roots and shoot of identically grown plants of salt sensitive varieties of barley maintained their growth rates and shoot to root ratio after an exposure to NaC1 for at least ten days in combination with unchanged levels of endogenous cytokinins. After ca 14 days NaC1 induced severe decreases in RGR values, but not in shoot to root ratio. Addition of benzyladenine inhibited growth to some extent and enhanced the cytokinin concentration.It was concluded, that cytokinin concentrations measured directly after exposure to NaC1 form a promising screening method for salt resistance. The addition of BA made salt resistance varieties behave as salt sensitive varieties.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.